Telephone answering apparatus in general is well known in the prior art. Such apparatus responds to an incoming telephone ring signal to transmit a recorded announcement to the calling party during a first time interval (T.sub.1), and then automatically to enter a message recording mode during a second time interval (T.sub.2) during which the message from the calling party is recorded. A first type of the prior art telephone answering apparatus is constructed so that the second time interval (T.sub.2) is of a fixed length, and others are constructed so that the second time interval (T.sub.2) continues so long as the calling party is talking.
The prior art telephone answering apparatus, for the most part is complex in its construction, and incorporates complicated relay circuits involving a multiplicity of mechanical relays, in order to achieve the required switching functions. The prior art apparatus also generally involves relatively complicated controls and other electronic circuits. A simplified type of telephone answering apparatus is described and claimed in copending application Ser. No. 481,966 which was filed June 24, 1974 in the name of the present inventor, and which is assigned to the present assignee. The telephone answering apparatus described in the copending application is constructed to retain all the basic features and functions of the prior art systems and apparatus, and yet to involve a relatively simple and inexpensive assembly, and to include relatively simple electronic controls and circuitry.
The apparatus of the present invention is generally similar to the apparatus described in the copending application. However, in the apparatus of the present invention the announcement tape is embodied in a cassette-type unit, rather than being permanently incorporated into the apparatus, as is the case in the prior application. Also, in the apparatus of the present invention a single irreversible drive motor which is used to drive both the announcement and message tape units, instead of reversing the direction of rotation of the motor for the rewind operation of the message tape unit, as is the case in the apparatus described in the copending application, reversal is achieved through a mechanical coupling assembly, which will be described. Such a construction permits one of the motor leads to be connected to a grounded noise shield, to reduce motor noise in the reproduced signals during the playback operation. It is not feasible to ground one of the motor leads in the apparatus of the prior application, so that noise attenuation cannot easily be achieved in the reversible type motor apparatus.